TS-Optics 90mm F6,6 FPL-53 Triplet APO Objective in Cell

TS 90mm f/6.6 FPL-53 Triplet APO lens in mount

For amateur telescope making (refractor, bino, telephoto lens ...)

The color correcture of this objective is very close to LZOS. Even at highest magnifications, the image is kept free of false colour and has a high grade of correction. The fast f/6 system is not only short and compact, you will have very faint and small stars without blue halo and it is also good for planetary observing or imaging.
The new Triplet lens offers a fully apochromatic performance. Through use of high quality FPL-53 ED glass from Ohara (Japan) a very consistent quality is guaranteed. In the spot diagram below you can see how well the APO Objective is corrected!
Of course the lens is fully multi-coated for a bright and clear image. The adujstable lens is air spaced - not cemented.

Image Quality of the TS Optics APO 90mm Objective - SPOT diagrams and star test

The Spot Diagram is ideal for judging the colour correction of a telescope, not only on the optical axis, but also off axis. The black rings are the airy discs. As you can see all wavelengths between 500nm and 700nm are kept inside the airy disc. Off axis (second line: 1/4°, third line: 1/2°) the colour is still very well corrected - just compare this with some very expensive APO Objectives.





The Star Test on our artificial star is equivalent to the image of a real star at a magnification around 200x. But please note that our artificial star works in autocollimation. This means that whatever optical defects there are, you will see the effects twice as strongly as on a real star!

Images from left to right:

far inside of focus

slightly inside of focus

a focused medium magnitude star (around 5-6 mag)

a focused bright star (e.g. Vega)

slightly outside focus

far outside focus

As you can see false colour is virtually nonexistent in focus. You can also see that the star is well centered. This also shows that the lens is not pinched inside its cell.